I own and buy dilapidated properties and always have a plumbing issue to address in these properties. On a number of them, I've just taken the property to the studs and re-wire and plumbed the property for peace of mind more than anything. However, on a couple other properties, I've just worked with the existing layout.

If I have good bones, but older plumbing, would you suggest just making upgrades to the existing plumbing where we can access it or with today's new products is it always just better to start from scratch? Keep in mind, budget is always a factor! haha

For all sinks and showers, I replace the exposed plumbing with new. This is particularly true for new ABS tail pieces and p-traps and angle stops. All faucets and shower mixers get replaced too.

This is not just a liability thing . . . it really helps buyer appeal because it gives the sense of a well upgraded/repaired house. You have to assess things like granite or plastic or tile . . . new counter tops and sinks . . .

Also, I replace every receptacle and wall switches routinely. Presents a clean and updated look that buyers do notice. These items are cheap and easy to replace but the impact is a big plus.